Re: [PATCH -fixes] riscv: Fix arch_tlbbatch_flush() by clearing the batch cpumask

From: Palmer Dabbelt
Date: Wed Feb 07 2024 - 14:35:22 EST


On Wed, 07 Feb 2024 11:23:55 PST (-0800), samuel.holland@xxxxxxxxxx wrote:
Hi Alex,

On 2024-01-30 5:55 AM, Alexandre Ghiti wrote:
We must clear the cpumask once we have flushed the batch, otherwise cpus
get accumulated and we end sending IPIs to more cpus than needed.

Fixes: 54d7431af73e ("riscv: Add support for BATCHED_UNMAP_TLB_FLUSH")
Signed-off-by: Alexandre Ghiti <alexghiti@xxxxxxxxxxxx>
---
arch/riscv/mm/tlbflush.c | 1 +
1 file changed, 1 insertion(+)

diff --git a/arch/riscv/mm/tlbflush.c b/arch/riscv/mm/tlbflush.c
index 99c3e037f127..c8efc3f87a0f 100644
--- a/arch/riscv/mm/tlbflush.c
+++ b/arch/riscv/mm/tlbflush.c
@@ -240,4 +240,5 @@ void arch_tlbbatch_flush(struct arch_tlbflush_unmap_batch *batch)
{
__flush_tlb_range(NULL, &batch->cpumask,
0, FLUSH_TLB_MAX_SIZE, PAGE_SIZE);
+ cpumask_clear(&batch->cpumask);
}

This patch doesn't apply to fixes -- it looks like it was based on "riscv: Call
secondary mmu notifier when flushing the tlb"[1], which has not been merged and
would go in for-next anyway. Otherwise:

Reviewed-by: Samuel Holland <samuel.holland@xxxxxxxxxx>

[1]: https://lore.kernel.org/all/20240124080325.2324462-1-alexghiti@xxxxxxxxxxxx/

Ya and for some reason it trips up "patch -p1", which applies it to some other function. I just merged it manually a few minutes ago and it's in the tester...